1. Field of the Invention
The invention is directed to a vibration damper with adjustable damping force.
2. Discussion of the Prior Art
German reference DE 195 42 293 A1 describes a vibration damper with adjustable damping force, wherein the vibration damper comprises a cylinder with an axially movable piston which is fastened to a piston rod and which divides the cylinder in two work spaces. An externally adjustable damping valve is connected to one of the work spaces and throttles the damping medium which is displaced from the adjoining work space so that a damping action takes place. The externally adjustable damping valve has no fixing means for a determined damping force adjustment which should be reproducible.
German reference DE 197 24 328 C1 shows a further development of DE 195 42 293 A1. A locking device has been assigned to the damping valve to enable a desired adjustment of damping force in an exactly reproducible manner. The damping valve according to DE 197 24 328 A1 does not present any difficulties with respect to function. The problem lies in the difficult assembly because a large number of structural component parts, some of which are very small, must be assembled under pretensioning by spring. The expenditure on manual assembly is considerable.
European reference EP 0 601 982 B1 discloses a damping valve which is formed of two valve cartridges for different pressure ranges. The exact construction of the valve is not described. However, there is a locking device by which a valve adjustment can be reproduced once it has already been adjusted. For assembly, a pressure spring of more robust dimensioning is first inserted into a valve receiving opening. The bottom part of a valve housing is then inserted into the valve receiving opening until it contacts the pressure spring. The bottom part of the housing receives a valve body which is pretensioned by a closing spring. The closing spring is supported at a spring clamp whose rear side contacts a top part of the valve housing which is screwed into the valve receiving opening. An adjusting cap which is connected by a clamping screw with the spring clamp is fitted to the top part of the valve housing. This assembly also involves considerable expenditure because, in addition to the pressure spring and the closing spring, several additional springs of the locking device act on the adjusting cap, which makes handling of the entire damping valve more difficult.
Accordingly, it is an object of the present invention to provide an adjustable damping valve which is improved with respect to ease of assembly.
According to the invention, this object is met in that the housing of the damping valve is closed on the end by a cover which has, on the outer side, a contact or engagement for the adjusting means which can be mounted separate from the damping valve.
The essential advantage compared to the prior art cited above is that the adjusting means and the actual damping valve form two constructional units which can be mounted separately and each of which can be closed in itself. Assembly is appreciably facilitated by the strict function and spatial separation of the two damping valve constructional units.
In a further embodiment, the adjusting means have a fastening ring for the damping valve in which an adjusting bolt or adjusting pin is arranged, wherein locking means engage between the adjusting pin and the fastening ring. The fastening ring takes over the function of spatially holding the adjusting means and the adjusting pin takes over the adjusting movement function.
Accordingly, it is provided that the fastening ring, depending on the provided damping force steps of the damping valve, has locking recesses in which a locking body engages, which locking body is pretensioned by spring force. The locking device connects the fastening ring and the adjusting pin to a sufficient extent to form a constructional unit.
According to another embodiment, the locking recesses are constructed in the circumferential direction in the fastening ring, so that the adjusting pin carries out a rotational operating movement.
For the purpose of a simple transmission of the adjusting movement, a wrench connection is provided between the adjusting pin and the cover of the damping valve housing which transmits a rotational movement of the adjusting pin to the cover and changes the distance between the base and the cover of the damping valve housing by means of a transmission arrangement.
In order that the mounting process for the two constructional units, namely, the adjusting means and damping valve, proceeds as quickly as possible, the damping valve housing has torque transmission surfaces in the direction of the fastening ring which are contacted by corresponding contact surfaces of the fastening ring, so that the screwing in movement of the fastening ring is transmitted to the damping valve housing. A further advantage is that the tool for screwing in the damping valve housing is greatly simplified. A commercially available crescent wrench, ring wrench or open jaw wrench can be used on the fastening ring.
In this further embodiment, the adjusting pin travels over an axial engagement path in the wrench connection to the cover of the damping valve housing relative to the fastening ring independent from the common mounting movement of the constructional unit comprising the adjusting means and damping valve.
In this regard, the fastening direction has two rows of locking recesses in an axial arrangement, wherein one row defines the position of the adjusting pin in which the wrench connection between the cover of the damping valve housing and the adjusting pin is not engaged.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.